What extension cab for gk mb 115 2

I just picked up one of these today at a boxing day sale for $375 and am impressed so far. I was just wondering how to use the output on the back.

Is it to just hook up to a powered cab, or another GK MB 115 II. I assume the later, but the only info I can find online are of the older silver grilled made in China version, which I tried 3 of and they all had distortion and farting problems.